Flocculation apparatus

ABSTRACT

Rotary paddles of a mixing apparatus are driven by a crank mechanism through a pivoting lever that swings about a yieldable fulcrum, the arrangement being such that the paddles are moved with a varying velocity in a circular path through the liquid being mixed.

United States Patent I Philip Edgerton Hollcong, Pa. 786,070

Dec. 23, 1968 Aug. 31, 1971 FMC Corporation San Jose, Calif.

lnventor Appl. No. Filed Patented Assignee FLOCCULATION APPARATUS 4Claims, 4 Drawing Figs.

US. Cl

Field of Search References Cited UNITED STATES PATENTS 1,432,358 10/1922Podhajny 259/109 1,699,916 1/1929 Platin 259/109 2,081,850 5/1937 Darby259/110 Primary Examiner-Robert W. Jenkins Attorneys-F. W. Anderson andC. E. Tripp ABSTRACT: Rotary paddles of a mixing apparatus are driven bya crank mechanism through a pivoting lever that swings about a yieldablefulcrum, the arrangement being such that the paddles are moved with avarying velocity in a circular path through the liquid being mixed.

PATENTEU M1831 l97| INVENTOR. PHILIP EOGERTON BYJU. W

AT TORN E YS FLOCCULATION APPARATUS BACKGROUND OF THE INVENTION In thetreatment of sewage and the like by chemical flocculation, the rapidthorough mixing of chemicals with raw water, sewage or industrialliquids is followed by a gentle, slow mixing to produce a maximum sizefloc. It has been found that it is advantageous to move the mixture witha circular rolling movement to keep the floc in suspension, and it hasalso been found that the growth of floc is dependent upon relativemovement between the paddles and the mixture. Reciprocating andoscillating mixers have been proposed but, while they do attain a degreeof relative movement between the paddles and the mixture, they do notmaintain a continuous roll velocity that is effective to keep the flocin suspension. Accordingly, with reciprocating and oscillating mixersthe solid material tends to settle out and become deposited on thebottom of the mixing tank rather than moving along toward a desireddischarge station. Accordingly, it is an object of the present inventionto provide a novel mixing apparatus that is effective to move a mixtureof liquids and solid material in such a manner that the solids aremaintained in suspension while the elements of the mixing mechanism moverelative to the mixture to promote flocculation.

SUMMARY OF THE PRESENT INVENTION A mixing mechanism, comprising a pairof rotary paddle assemblies keyed to a horizontal shaft, is disposed inan elongated tank, submerged in a mixture of raw water, chemical andsewage. The horizontal shaft is driven from a variable speed drive unit,that is mounted at the top of one end wall of the tank, through a drivemechanism which consists of an upper crank connected to the rotaryoutput shaft of the drive unit, a lower crank keyed to the horizontalmixer shaft, and a drive lever connected between the cranks.

Rotation of the upper crank in one direction effects rotation of thelower crank in the opposite direction due to the provision of a fulcrumunit that is mounted in fixed position in the tank adjacent the drivelever. The fulcrum unit comprises a pair of rollers that bear againstopposite sides of the drive lever to provide pivot points for the leveras it responds to the movement of the upper crank. Each roller ismounted to move laterally relative to the lever to accommodate lateralmovement of the central portion of the lever as it transmits the motionof the upper crank to the lower crank.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic side elevation ofthe mixing apparatus of the present invention shown in operatingposition in a tank.

FIG. 2 is a diagrammatic vertical section taken on line 2-2 of FIG. 1.

FIG. 3 is an enlarged diagrammatic view of a portion of FIG. 2,particularly showing the operation of the rollers of the fulcrum unit.

FIG. 4 is a fragmentary diagrammatic showing of a second embodiment ofthe mechanism of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. I the reference numeral 10indicates generally a concrete tank having an inlet opening 12 formed atthe upper end of one wall, a-discharge opening 14 at the upper end of anopposite wall, and a pair of fixed piers 16 and 17, supported from thefloor of the tank and projecting up into the mixing chamber defined bythe walls of the tank. Three wooden baffle units 18, 20 and 22 aremounted in fixed position to extend transversely across the tank fromone sidewall to the other.

A generally horizontal shaft 24 is rotatably journaled in bushings 26,27 and 28 that are mounted respectively on the pier 16, the pier 17, andon a bracket 30 supported from the tank wall. Two paddle assemblies 31and 32 are keyed to the shaft 24 in 90, out-of-phase relation. Eachpaddle assembly comprises a pair of metal arms 34 that are mounted atspaced intervals along the shaft 24, each of the arms 34 includingmembers 34a and 34b (FIG. 2)' that project in opposite directions from afabricated square hub 36 which is secured to I the shaft 24 for rotationtherewith. A plurality of wooden paddles are secured between each pairof arms 34.

The shaft 24 is driven from a motor driven speed reducer 40 (FIG 1)which has an output shaft 41 to which an upper crank 42 is keyed. Apivot lever 44 that is rectangular in cross section, is pivotallyconnected at its upper end to the upper crank by a pin 45; and at itslower end it is pivoted by means of a pin 46 to a lower crank 47 that iskeyed to the horizontal mixer shaft 24.

Referring to FIG. 3 it will be noted that, as indicated by directionarrows, when upper crank 42 rotates counterclockwise, the lower crank 47and shaft 24 rotate clockwise. This reversal is effected with the aid ofa fulcrum assembly 50 through which the pivot lever 44 passes. Theassembly 50 comprises a housing 52 that is open at the top and bottomand is secured, as by bolts, to the end wall of the tank directly belowthe drive unit 40. The fulcrum assembly provides a pair of fulcrumrollers 54 and 55 that are rotatably mounted on bellcrank assemblies 56and 57 respectively and are in the plane of the fiat pivot lever 44 inposition to contact the side edges of the lever. Each bellcrank assemblyincludes a pair of spaced levers 58 and 59 that are pivoted on a shortshaft 60 that extends horizontally between the sidewalls of the housing52, each lever being provided with a flat contact plate 62 along theedge of one of its arms. The contact plates 62 of the two bellcrankassemblies are in the path of movement of a pair of rollers 65 (FIG. 1)that are rotatably mounted on opposite faces of the pivot lever 44. Astop member 67 is secured to the levers 58 and 59 of the bellcrankassembly 56 and is effective to engage a fixed abutment 68 of thehousing 52 for the important purpose of limiting the clockwise rotationof the bellcrank which must at all times extend into the path-of theroller 65, and has its weight distributed to pivot to that position, butmust be prevented from interfering with the operation of bellcrank 57.

In FIG. 3 an operating position of the mixer drive mechanism isillustrated wherein the upper crank 42 and the lower crank 47 havereached a lower dead center position and the pivot lever is in asubstantially vertical position. It will be noted that the rollers 65have engaged the contact plates 62 of bellcrank assembly 57 and areexerting a force tending to pivot the bellcrank counterclockwise tobring the fulcrum roller 55 into contact with the side edge of the pivotlever 44 and to hold it tightly against the lever as the cranks movethrough the dead center position. Thus, the roller 55 acts as a fulcrumand the movement of the upper end of the lever 44 causes the lever topivot clockwise about roller 55 and thereby positively move the lowerend of the lever 44 clockwise. As a result, the lower crank 47 and mixershaft 24 rotate clockwise. The reverse action takes place when therollers 65 move upwardly and engage the contact plates 62 of bellcrankassembly 56.

Since paddles 35 move continuously in a circular path, the mixture ismoved with a continuous rolling action that keeps the solid material insuspension. Further, it should be noted that, while the upper crank 42rotates with constant angular velocity, the lower crank 47 rotates at avariable speed which is a minimum at upper dead center and maximum atlower dead center. Therefore, the mixer shaft 24 rotates at a variablespeed and the blades 35 are continuously changing their velocityrelative to the mixture, resulting in a shearing action that promotesflocculation.

In FIG. 4 there is disclosed a second embodiment 70 of the presentinvention wherein a pivot lever 44', which is identical to the pivot 44of FIG. 2 except that it has no actuating roller similar to the roller65, is disposed in a tank and driven by upper and lower cranks exactlyin the manner that pivot lever 44 is driven. Laterally shiftablefulcrums are provided by a unit 71 including a mounting plate 72 securedto the end wall of the tank, two spaced brackets 73 and 74 fixed to theplate 72 and a pair of slide rods 76 and 77 that are slidably journaledin the brackets 73 and 74 respectively. Also'included in the unit are aroller 78 rotatably mounted on the bifurcated end of rod 76, a roller 79similarly mounted on rod 77, and a spring 80 disposed between eachbracket and a flange on the associated slide rod to urge the roller onthe rod into engagement with the adjacent side face of the pivot lever.

It will be evident that the spring-urged rollers maintain contact withthe pivot lever and provide the fulcrum that is necessary to guide thepivot lever in its pivoting and slight lateral shifting movement.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention as set forth in theappended claims.

Iclaim:

1. Apparatus for concentrating floc in a tank comprising mixing membersmounted for movement in a circular path in the tank, and means fordriving said mixing members at varying speed, said drive means includinga driving and a driven crank operatively connected to said mixingmembers, a pivot lever connected between said cranks, bellcranks mountedfor pivotal movement on opposite sides of said lever, each bellcrankcarrying a rotatable roller movable into engagement with said lever, toprovide a fulcrum for said lever incident to pivoting of saidbellcranks, actuating means on said pivot lever for alternately engagingand pivoting said bellcranks, as said lever moves up and down inresponse to rotation of said driving crank, and abutment means in thepath of one of said bellcranks for limiting the pivoting of one of saidbellcranks to prevent interference of said bellcranks during movement ofsaid pivot lever.

2. Apparatus according to claim 1 including a housing pivotally mountingsaid bellcranks and wherein said abutment means is disposed on saidhousing to be contacted by said one bellcrank.

3. Apparatus for concentrating floc in a tank comprising mixing membersmounted for movement in a circular path in the tank, and means fordriving said mixing members at varyingspeed, said driving meansincluding a driver crank, a driven crank, a pivot lever pivotallyconnected to each crank and disposed for generally up and down movementbetween said cranks and pivoting movement in a predetermined plane, inresponse to rotation of said driver crank, means connecting said drivencrank to said mixing members to move said members in a circular path,pivot control means for said pivot lever for guiding said lever in anorientation such that rotation of said driver crank in one directioncauses rotation of said driven crank in an opposite direction, saidcontrol means including a pair of fulcrum rollers disposed on oppositesides of said pivot lever in said plane, each roller being locatedsubstantially midway between said driver and driven cranks, and springmeans urging said rollers for movement in said plane into contact withsaid lever to provide fulcrums therefor during up and down movement ofsaid lever.

4. Apparatus for concentrating floc in a tank comprising a plurality ofpaddles mounted for rotation in the tank, and means for moving saidpaddles in a circular path through a mixture of liquid and solidmaterial in the tank, including means for varying the speed of movementof said paddles between upper and lower limits of speed during movementin said circular path for causing said paddles to move through themixture at varying speeds with a shearing action, superposed on thecircular movement of said mixing members and for moving the mixture witha circular rolling action that keeps said solid material in suspension.

1. Apparatus for concentrating floc in a tank comprising mixing membersmounted for movement in a circular path in the tank, and means fordriving said mixing members at varying speed, said drive means includinga driving and a driven crank operatively connected to said mixingmembers, a pivot lever connected between said cranks, bellcranks mountedfor pivotal movement on opposite sides of said lever, each bellcrankcarrying a rotatable roller movable into engagement with said lever, toprovide a fulcrum for said lever incident to pivoting of saidbellcranks, actuating means on said pivot lever for alternately engagingand pivoting said bellcranks, as said lever moves up and down inresponse to rotation of said driving crank, and abutment means in thepath of one of said bellcranks for limiting the pivoting of one of saidbellcranks to prevent interference of said bellcranks during movement ofsaid pivot lever.
 2. Apparatus according to claim 1 including a housingpivotally mounting said bellcranks and wherein said abutment means isdisposed on said housing to be contacted by said one bellcrank. 3.Apparatus for concentrating floc in a tank comprising mixing membersmounted for movement in a circular path in the tank, and means fordriving said mixing members at varying speed, said driving meansincluding a driver crank, a driven crank, a pivot lever pivotallyconnected to each crank and disposed for generally up and down movementbetween said cranks and pivoting movement in a predetermined plane, inresponse to rotation of said driver crank, means connecting said drivencrank to said mixing members to move said members in a circular path,pivot control means for said pivot lever for guiding said lever in anorientation such that rotation of said driver crank in one directioncauses rotation of said driven crank in an opposite direction, saidcontrol means including a pair of fulcrum rollers disposed on oppositesides of said pivot lever in said plane, each roller being locatedsubstantially midway between said driver and driven cranks, and springmeans urging said rollers for movement in said plane into contact withsaid lever to provide fulcrums therefor during up and down movement ofsaid lever.
 4. Apparatus for concentrating floc in a tank comprising aplurality of paddles mounted for rotation in the tank, and means formoving said paddles in a circular path through a mixture of liquid andsolid material in the tank, including means for varying the speed ofmovement of said paddles between upper and lower limits of speed duringmovement in said circular path for causing said paddles to move throughthe mixture at varying speeds with a shearing action, superposed on thecircular movement of said mixing members and for moving the mixture witha circular rolling action that keeps said solid material in suspension.